Accessible tab panel using ARIA and Vanilla Javascript

Robust and accessible

As it relies on a normal HTML structure (a list of links with internal anchors), even if the JavaScript isn’t loaded, your page will work: it’s the miracle of progressive enhancement;
it is based on ARIA Design Pattern for tabpanel;
No inline CSS/JavaScript injected, your DOM stays clean, which is cool for responsive.

It’s (highly) customisable

You can style it as you want;
You can set up transitions… as you want;
You can create namespaces for generated classes;
Every aspect of the script can be customized, if you transpile the script into ES5, it will be IE9+ compatible.

Free and no license problem

No license problem: it uses MIT license, so it’s free, open-source and you can do whatever you want with it, including commercial use. This permission notice shall be included in all copies or substantial portions of it.
However, it is not prohibited to tell me that you’ve used it, or send me a little “thank you”. ;)

Lightweight

20kb (development, readable by humans);
6kb (minified, readable by machines);
2kb minified and gzipped (readable by… mutants‽‽)

How it is working

ARIA is coming

The script adds all needed attributes to your tabs controls and panels (role="tab/tablist/etc.",aria-selected/controls="…").

Then a bit of styling classes

Then it will generate some classes for you, to allow styling your tabs as you want.

And JavaScript does the rest

Some listeners for keyboard and mouse interactions are added, when you activate one, it will updates attributes and manage keyboard interations.

How to use it

Download the script

You may also use npm command: npm i van11y-accessible-tab-panel-aria.
You may also use bower: bower install van11y-accessible-tab-panel-aria.

Conventions

Then, follow the conventions given in this minimal example (in bold).

use classes needed (js-tabs, js-tablist, js-tablist__item, js-tablist__link, js-tabcontent)
check that your anchors are working.
for accessibility purposes (for VoiceOver), the plugin has to give focus to hx (h2, h3, h4, etc.) in tab contents.

For Hx, you have two cases:

There aren’t any in your js-tabcontent’s, so specify in data-hx attribute (will be added with class="invisible", which means visually hidden);
There are some, just tell it to the plugin using data-existing-hx attribute.

Example without hx:

<div class="js-tabs">
  <ul class="js-tablist" data-hx="h2">
   <li class="js-tablist__item">
    <a href="#id_first" class="js-tablist__link">1st tab</a>
   </li>
   <li class="js-tablist__item">
    <a href="#id_second" class="js-tablist__link">2nd tab</a>
   </li>
  </ul>
 <div id="id_first" class="js-tabcontent">
   here the content of 1st tab
 </div>
 <div id="id_second" class="js-tabcontent">
   here the content of 2nd tab
 </div>
</div>

Example with hx:

<div class="js-tabs">
  <ul class="js-tablist" data-existing-hx="h2">
   <li class="js-tablist__item">
    <a href="#id_first" class="js-tablist__link">1st tab</a>
   </li>
   <li class="js-tablist__item">
    <a href="#id_second" class="js-tablist__link">2nd tab</a>
   </li>
  </ul>
 <div id="id_first" class="js-tabcontent">
   <h2>title</h2>
   here the content of 1st tab
 </div>
 <div id="id_second" class="js-tabcontent">
   <h2>other title</h2>
   here the content of 2nd tab
 </div>
</div>

These examples are taken from the demo.

The script is launched when the page is loaded. If you need to execute it on AJAX-inserted content, you may use for example on <div id="newContent">your tab panel source</div>:

van11yAccessibleTabPanelAria(document.getElementById('newContent'));

Keyboard shortcuts

If you focus on the tabs “buttons”:

use Up/Left to see previous tab,
use Down/Right to see next tab
use Home to see first tab (wherever you are in tab buttons)
use End to see last tab (wherever you are in tab buttons)

If you focus on a tab content:

use Ctrl Up/Left to set focus on the tab button for the currently displayed tab
use Ctrl PageUp to set focus on the previous tab button for the currently displayed tab
use Ctrl PageDown to set focus on the next tab button for the currently displayed tab

Warning: Ctrl+PageUp/PageDown combination could activate for some browsers a switch of browser tabs. Nothing to do for this, as far as I know (if you have a solution, let me know).

Logic of styling classes

Before Javascript

Once you set up the code with your content, style it before activating JavaScript: so it will be nice even if there is no JavaScript.

For example, just imagine you are on poor mobile connexion, and the JavaScript hasn’t (yet) loaded. Or it can be disabled.

After Javascript

You should add classes to the source, and use them this way:

[role="tablist"].my-style {…}

Basically, you should rely on ARIA attributes, so styles will be applied only if JavaScript is loaded and well-executed.

Namespaced generated classes

The plugin has another feature: if you don’t like styling on role attributes, it can generate classes for you only for styling tabs when they are activated.

Here is an example:

<ul … data-tabs-prefix-class="last-tabs">

The data-tabs-prefix-class will add classes on each elements:

<ul … class="… last-tabs-tabs__list">
  <li … class="… last-tabs-tabs__item">
    <a … class="… last-tabs-tabs__link">…

So with data-tabs-prefix-class="last-tabs" you have:

last-tabs-tabs__list for styling the ul;
last-tabs-tabs__item for styling the li;
last-tabs-tabs__link for styling the a;
last-tabs-tabs__content for styling each tab panel.

Bonuses

Tab panel opened by default

If you need a tab to be opened by default, it is possible, using data-selected="1" on the .js-tablist__link you need to be opened (See the demo, second example).

Other tabs are still available, here are the rules for this feature:

The fragment detection (explained below) will always have priority on this feature;
If there are several data-selected="1" put on tabs in the same group (which does not make sense and should never happen), the first one will be used.

Anchor added in URL

As you may notice (or not), now the script adds a fragment in the URL when you click or select a tab using the keyboard. It is cool when you want to copy/paste the link of the page you are reading, and the opened tab will be the good one!

Anchor on a tab panel

If you need to make a link on your page to a id that is on a tab panel, the script will detect it and display the good tab, only for you.

If you want to test, open a new window, and copy/paste this:
https://van11y.net/downloads/tab-panel/demo/index.html#id_third

Anchor in a tab panel

If you need to make a link on your page to a id that is in a tab panel, the script will detect it and display the good tab, only for you.

If you want to test, open a new window, and copy/paste this:
https://van11y.net/downloads/tab-panel/demo/index.html#cool-anchor

“In-page” link to a tab panel

If you need to create in your current page a link to a tab (inside or outside), it is possible:

Create the link to the content you want to target: <a href="#link-to-tab">link to tab option</a>;
Add the class class="js-link-to-tab" to it;
And that’s all. The plugin will make it work.